Delayed Neutron Emission in the Decays of Short-Lived Separated Isotopes of Gaseous Fission Products

Beta-decay properties of the neutron-rich 94–99Kr and 142–147Xe isotopes

“…The sensitivity of these parameters to the different parts of the β strength is determined by the strong energy dependence of the Fermi function, (Q β -E) 5 . As the β-strength function depends on nuclear structure, the measured T 1/2 and P n do as well.…”

“…Since then there has been surprisingly little progress in the investigation of neutron-rich Kr and Xe nuclei. A number of short-lived Kr and Xe isotopes were measured at various ISOL facilities [4][5][6][7][8][9][10][11], however, these studies were limited to 91−94 Kr and 139−143 Xe. The heaviest noble-gas isotopes known so far, 95 Kr and 144,145 Xe [12], were in fact obtained in earlier experiments utilising emanation, chemical separation and gas-jet techniques [13][14][15][16][17].…”

Rapid Chemical Separations

“…For the study of krypton, xenon, and radon isotopes pro duced by spallation, the oxide hydrates of zirconium, cerium(IV) , and thorium, respectively, were bombarded with high-energy protons (27,95). The transfer from the target to the separator through long, evacuated tubes needed about 10 to 20 seC (95,106,109). Nonetheless, products with half lives of a few seconds were studied, e.g.…”

“…For the study of fission products, uranyl stearate was irradiated in low thermal-neutron fluxes (106) or fission fragments recoiling' from a 252C£ source were stopped in barium stearate (107,108). A uranium dioxide target was placed inside a reactor (109,110) where it was self-heated to ,..., , 6000 C (111). For the study of krypton, xenon, and radon isotopes pro duced by spallation, the oxide hydrates of zirconium, cerium(IV) , and thorium, respectively, were bombarded with high-energy protons (27,95).…”

Gamma ray decay schemes for 142XE, 142CS, 142BA, 142LA

“…initial studies performed with the TRISTAN system on A = 142 nuclei were directed towards the establishment of accurate half-lives and delayed neutron emission ratios; these results have been reported in the literature (52,53), and are shown in summary in Fig. 6.…”